Not sure, this question is in the correct section. We were hoping to do our extension on a building notice, but since we have a sewer running under our house and proposed extension we have to get building regulations approval. Having gone through the regulations most seem fairly straightforward once we have appointed structural engineers, apart from drainage, part H, which has me totally confused.
We have a 1950's bungalow which has been extended in all directions by previous owners, including a part length rear extension which has a sewer running under it serving at least three properties. This extension was built prior to adoption of shared sewers by the water companies, in this case Thames Water.
Our planning permission extends this rear extension to the full length of the house, so we will be building further over the sewer, for which we need prior approval by Thames Water. At present there are two manholes in our garden, one on entering the garden, the other under the proposed extension which will have to be moved or removed. If we move the manhole in line with the sewer, there is only a gap of c. 97 cm between the house and the garage where it can go.
Do we need this second manhole? Can we build it in such a small gap? We may be better to divert the sewer from under the house around the garden is this easy/ possible and how many manholes would we need?
Any suggestions/ advice would be much appreciated.
existing plan.PDF
proposed plan.PDF
proposed site plan.PDF